In Prostate CA, Sexual Decline After Radiation Has Limit

Action Points

Explain to patients that this study suggested that sexual function declines for two years after external-beam radiation therapy for prostate cancer but then stabilizes thereafter.

Sexual function declines in the first two years after external beam radiation therapy for prostate cancer but stabilizes thereafter, according to data from a prospective cohort study.

All parameters of sexual function declined significantly (P<0.05) in the first two years after external-beam radiation therapy (EBRT), Richard Valicenti, MD, of the University of California Davis, and colleagues found.

But for years two through six of follow-up, none of the evaluated parameters of sexual function changed significantly.

Pretreatment sexual function was the strongest predictor of sexual function at any time after EBRT, the investigators reported in the January issue of the International Journal of Radiation Oncology*Biology*Physics.

Their findings debunk the perception that sexual function declines continually after radiation therapy for prostate cancer.

"The results of this study allow patients and their partners to have a fuller understanding of the long-term sexual side effects of EBRT, and what they can expect after treatment should aid in deciding on a treatment course," Valicenti said in a statement.

Reported rates of impotency after EBRT for prostate cancer have ranged from 8% to 85%, a variation the authors attributed to the different instruments used to assess sexual function. Moreover, many studies included men who received androgen deprivation therapy in addition to EBRT, possibly masking the contributions of radiation therapy to changes in sexual function.

Several recent studies have suggested that rates of sexual dysfunction increase with follow-up. However, few studies included pretreatment assessment of sexual function or conducted serial assessments of sexual function after EBRT, the authors wrote.

To shed more light on the question, the investigators prospectively followed 143 men who completed a sexual function questionnaire prior to EBRT for prostate cancer and at each follow-up visit. The questionnaire assessed four domains of sexual function: sexual drive, erectile function, ejaculatory function, and overall satisfaction.

The mean age of the patients was 69, median Gleason score was 6, and median total radiation dose was 73.8 Gy (range of 66.6 to 79.2 Gy).

During a median four-years of follow-up, the study participants completed a total of 1,187 questionnaires. Some patients were followed for as long as eight years after EBRT.

Baseline scores for sexual drive and erectile function were significantly associated with patient age (P=0.003 and P=0.004, respectively). Ejaculatory function was significantly associated with age, race, and marital status (P<0.05).

Scores on all four domains of sexual function, as well as the total score, declined significantly in the first two years after EBRT (P<0.05) compared with baseline values.

Investigators grouped the patients according to baseline sexual function. Analysis of scores for patients above and below the median sexual function value showed that differences in sexual function persisted over time. Regression analysis showed that baseline score was the best predictor of later scores for all of the domains assessed (P<0.001).

A separate analysis of scores from years two through six showed no significant changes in any of the domains: sexual drive, P=0.067; erectile function, P=0.5; ejaculatory function, P=0.6; and overall satisfaction, P=0.44.

Baseline scores indicated that 74.1% of the study participants were sexually potent before EBRT. Among those who were potent before treatment, 74.4% remained potent at one year and 70.4% at two years after EBRT. The one- and two-year potency rates differed significantly from baseline, but the investigators found no statistically significant change in potency from years two through six.

"Our data have indicated that the widely held opinion that sexual function has a slow, progressive decline after EBRT might be incorrect," the authors wrote in conclusion. "Most sexual function decline in men undergoing EBRT for prostate cancer occurred in the first two years after treatment and all domains of sexual function, including erectile dysfunction, then appeared to stabilize."

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